It is known to measure voltage and current to ascertain the power consumption from a supply typically an alternating current supply, by generating signals corresponding to the voltage and current, producing a product of the two signals and integrating the result over a period of time.
In recent years development work has been concentrated on meters incorporating solid state devices for performing some of the computations. Potentially such devices allow more accurate measurement than older electromechanical designs of meter and will also enable remote reading to be incorporated more readily into such meters.
After manufacture (or refurbishment) it is necessary to calibrate such meters relative to some standard--usually by comparing the power reading obtained using the meter under test against that measured by a "standard" meter, and adjusting the former as appropriate.
It is an object of the present invention to provide power measuring apparatus which can be readily calibrated using a standard.
It is a further object of the invention to provide a method of calibration for power measuring apparatus and apparatus for calibrating said meters.